The invention relates to improvements in centrifugal separators and to an improved method of separating and an improved centrifuge of the type having a solid bowl driven in rotation with a worm therein driven independently of the bowl.
More particularly, the invention relates to an improved arrangement for the discharge of the solid fraction from the centrifuge in the manner in which the discharge is constructed.
German Letters Patent 27 29 057 discloses a solid bowl worm centrifuge for separating solids and liquid mixtures. The centrifuge has an outer shell or drum with a main cylindrical body portion and a conical end. The slurry is admitted through an opening into the drum and the liquid fraction is discharged at a first end, and openings are provided at a second end at the end of the conical portion of the shell for the discharge of the solids or sludge fraction. The walls of the opening extend either generally axially or can extend radially. Either radial or axial openings are used in approximately right angle or rectangular sharp deflection of the solids in the sludge fraction as the sludge fraction exits through the opening. This is particularly abrupt and vigorous because of the rotation of the drum and the necessity of the solids changing their path of action from a movement in one direction to a sharp radial movement. The movement is made more abrupt because of the centrifugal discharge caused as the drum is rotating.
As practice has shown, this abrupt and substantial deflection of the solids in the region of the solids discharge opening leads to rapid and high wear of the walls of the openings this is particularly true when substantial quantities of abrasive material are present, such as silica sands and the like which are often present in the solids so that the centrifuge must be frequently brought to a halt and laid up while repair is carried out. This involves a substantial disadvantage and a considerable outlay for work, time and cost of repair of the openings as well as the cost in shut down of the operation of the separator. Some centrifuges have been employed wherein the solids discharge occurs through nozzles arranged in the basket shell and the walls of these nozzles are also arranged to extend radially toward the outside and are affected by the same disadvantages.
Accordingly, an object of the present invention is to provide a method and apparatus which greatly reduces the wear at the walls of the solids discharge opening in a rotary centrifugal separator.
A further object of the invention is to provide an improved rotary centrifugal separator structure wherein openings for the sludge fraction are provided which are not subjected to rapid wear and wherein if wear occurs, the openings can be rapidly and easily repaired and replaced.
A still further object of the invention is to provide an improved centrifugal separator with a sludge discharge opening arrangement wherein the openings are uniquely structured and provided with wear inserts which are particularly constructed for sustaining wear and when wear occurs, for quick and rapid removal and replacement.
A further object of the invention is to provide exit openings for sludge from a rotary centrifugal separator wherein openings are so constructed to minimize wear and linings are provided for the opening which is situated so that wear is minimized.